Deflecting coil



Dec. 28, 19480 M. CAWEIN DEFLECTING 0011..

Filed May 24, ,1944

FIG.4

INVENTOR T0 POWER SOURCE MADISON CAWEIN ATTORNEY Patented Dec. ?8, 1948 UNITED STATES PATENT; OFFICE DEFLECTIN G COIL Madison Cawein, Fort Wayne, 11:11., assignor, by

meane assignments, to Corporation, a corporation of Indiana Application May 24, 1944, Serial No. 537,137 8 Claims. (Cl. 1752l) This invention relates generally to cathode-ray deflecting devices and is particularly directedto deflecting coils for use with a dissectortube to deflect an' electron beam. g

It is well known in the prior art to employ magnetic deflecting devices for deflecting a cathode ray in two directions substantially at right angles to each other. The deflecting device usually'consists of two pairs of deflecting coils, one pair being used for horizontal deflection and the other for vertical deflection. Each pair of coils consists of two halves. For developing a required field through the coils-currents of saw-tooth wave form are passed therethrough. w

In the construction of deflecting coils, it isa common practice "to wind the coil about a trapezoidal form, after which the windings are tied or taped together. Thereafter the coils are shaped to the desired curvilinear form and placed that when all the coils are arranged on the tube,

abulky coil system is formed. In 'the arrangement of the coils about the tube, it isnecessary to position one coilover the other, whereby the. winding of one coil is spaced a considerable distance from the electron beam emitted by the cathode, As a result, it is necessary to apply a greater voltage to the outermost coils to create a uniform flux fleld. Hence, it is seen that prior art coils are bulky and ineflicient.

It is theobject of this invention to provide a novel, compact cathode-ray deflecting device.

Another object of this invention is .to provide a deflecting device which is efflcient at scanning voltages of relatively low value.

In accordance with the present invention, there is provided a dissector tube having an electronemitting cathode and an electron-accelerating. anode. '-'Arranged about the tube intermediate the anode and cathode is a deflecting elementconsisting of a pair of cylindrical forms and a pair of coilswound thereon, each coil being arranged to provide magnetic flelds at right anglesIto. one another.

At the ends oi. each cylindrical form is a pair of notches. cylindrical forms which are telescoped over one another. Each form has single-layer windings disposed adjacent the inner walls thereof, the end conductors being wound through said notches and about the outer surface of the form, thereby The coils are wound on individual .Farnsworth Research 2 forming a coil that is compact and in the closest possible relation to the axis of the tube.

For a better understanding of the invention,

together with other and further objects thereof,

reference is made to the following description, taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the accompanying drawings:

Fig. 1 is an elevational view of a complete defleeting coil assembly inoperative relation with a dissector tube.

Fig. 2 is a sectional view taken on lines 22 on Pig- 1. I

Fig. 3 is a longitudinal section of one of the deflecting coils.

Fig. 4 is a perspective .view of a deflecting coil form showing the method of winding a coil.

Referring to the drawings, the dissector tube I comprises an evacuated envelope 2 containing an electron-emitting cathode 4 and an electron-accelerating anode 5. For-deflecting an electron beam emitted by the cathode with respect to the scanningaperture 8 of the anode, there is arranged about the envelope 2, intermediate the cathode and anode, two deflecting coils 1 and 8 disposed at right angles to each other so that horiaontal and vertical deflecting flelds are set up when said coils are connected to a suitable power source such as a saw-tooth wave generator 9 or ii.

Each deflecting coil is wound on an individual insulated cylindrical form such as l2 and iii, the form i2 being slightly larger in diameter than form i3. At the extreme ends of each form is formed a pair of diametrically-opposite notches I4 and l5; l6 and I! having diverging edge portions i8, i9, 20, 2|, 22, 23, 24 and 25,

Each coil consists of two halves having side windings 26 disposed against the inner walls of the forms and end windings 21 disposed around the outer-end surface of the form.

Referring to Fig. 4, there is shown a detailed arrangement of the two halves of one 'coil. The

' flrst turn .of the winding of the one half may be traced from the power source such, for example, as generator 9, Fig. 1, outside of the form i2 around the edge 20 of the notch 15, through the inside of the form to the opposite end thereof to the notch I1 and then outwardly and around the edge 24 of the notch I! and around the outer surface of the form to the diametrically-opposite notch it. This flrst turn is then wound inwardly and around the edge 22 of the notch l6 and ad- .iacent the inner surface of the form to the notch sired number of turns. The winding of the other half of the coil is substantially identical and when outer ends of the windings of each half are Joined to ether as at 28, the two halves form a unitary coil structure.

It is to be observed that the side portions 26 of the coil are uniformly laid parallel to each other and in a single layer whereby a uniform deflecting field is obtained which is very essential for successful operation of a cathode-ray tube. While there has been shown a coil structure of single-layer windings, it is to be realized that the coil may be wound with a-plurality of layers and thus provide a similar deflection field.

In operation, the deflecting coils I and 8 are positioned about the dissector tube substantially 90 apart for moving the electron beam emitted by the cathode I in two directions over the scanning aperture 8 of the anode. Current of "sawtooth wave" form is passed through the coils to develop the required magnetic field.

While there has been chosen a dissector tube to illustrate this invention, it is to be understood that the invention may also be applied to other forms of cathode-ray tubes such as the iconoscope, oscillight, kinescope or the orthicon.

While there has been described what is at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art'that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is: i

l. A magnetic deflecting element including a coil and a cylindrical form, said form being notched'at each end thereof, said coil consisting of a winding having its longitudinal conductors disposed on one surface of the form, the lateral end conductors being wound through each notch and about the other surface of the form.

2. A magnetic deflecting element comprising a form, a coil wound on said form, said form having a pair of notches formed at each end thereof to provide diverging edges adapted to support the windings of said coil, said coil consisting of longitudinal conductors disposed on one surface of said form, the lateral end portions of said conductors being laid around the adJacent diverging edges of each notch and around another surface of said form.

3. A deflection coil comprising a cylindrical form and a coil, said form including a pair of notches formed at each end thereof to provide diverging edges of the form adapted to support the winding of a coil, said coil consisting of a single-layer winding having two halves, each of which includes two paralle1 oppositely-facing single layers disposed adjacent the inner walls of said form, the end turns of each half being laid around the adjacent diverging edges of each notch and around the outer surfaces of the end portions of said form.

4. A magnetic deflecting element including a coil and a form, said form having cutaway portions at each end thereof to provide converging edge portions adapted to support the winding of said coil, said coil consisting of a winding having 4 a longitudinal part of its conductors on one side of the form and its lateral end conductors being wound around the converging edge portions to the other side of said form.

5. A deflection element comprising a cylindrical form and a coil, said form having end portions thereof cut away to form a pair of diametricallyopposite V-shaped notches at each end whereby to provide diverging edge portions adapted to support the windings of said coil, each pair of notches being in alignment with one another, said coil consisting of a single-layer winding having two substantially identical halves and consisting of two parallel oppositely-facing layers disposed adjacent said inner walls and between the aligned notches, the end turns of each half being laid around the adjacent diverging edge portion of each notch and around the outer sur faces of the end portions of said form.

6. A magnetic deflecting element comprising a form, said form having an outer and an inner wall and having end portions serrated to form a pair of diametrically-opposite V-shaped notches whereby to provide diverging edge portions, a coil wound on said form, said coil consisting of a sing1e-1ayer winding having two substantially identical halves and consisting of two parallel oppositely-facing single layers disposed adjacent said inner wall, the end turns of each half being laid around the adjacent diverging edge portion of each notch and around the outer surfaces of the end portions of said form.

7. Cathode-ray tube beam deflecting apparatus comprising a pair of coils and a pair of forms adapted to produce a magnetic field in two direcv tions, each of said forms being notched at each end thereof, and said coils consisting of windings having a part of their conductors disposed on one side of said form, the end conductors being wound through each notch and about the other side of said form.

8. Cathode-ray tube beam deflecting apparatus comprising a pair of coils and a pair of cylindrical forms telescoped over one another adapted to produce a pair of magnetic fields, each having a different direction and each of said forms being notched at each end thereof, each of said coils consisting of a winding having a part of its conductors disposed on the inner surface of one of said forms, the end conductors being wound through each notch and about the outer surface of the form.

MADISON CAWEIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 357,550 Chase Feb. 8, 1887 1,477,608 Taylor Dec. 18, 1923 1,546,424 Wood July 21, 1925 1,636,178 Gargan July 19, 1927 1,645,511 Birch-Field Oct. 18, 1927 2,074,764 Tolson Mar. 23, 1937 2,118,186 Fransworth May 24, 1938 2,236,498 Blain Apr. 1, 1941 2,269,678 Mauerer Jan. 13, 1942 FOREIGN PATENTS Number Country Date 239,586 Great Britain Sept. 10, 1925 

